Electrodeposition and characterization of nano-crystalline antimony telluride thin films

Electrodeposition is a promising low-cost method to fabricate nanostructured thermoelectric thin films such as Sb2Te3. However, electrodeposition of crystalline Sb2Te3 without the need for additional processing and with good compositional control has presented a challenge. Here we report on the electrodeposition of crystalline Sb2Te3 thin films at room temperature from a tartaric–nitric acid electrolyte using a pulsed, potentiostatic process. The effects of synthesis conditions on the resulting microstructure and compositional homogeneity are investigated using x-ray diffraction, electron diffraction, electron microscopy, and energy dispersive x-ray spectroscopy. The composition of the Sb–Te films was found to be dependent on the interval between pulses, a result that is likely due to the slow kinetics associated with Sb2Te3 formation at the surface. We also observed a change in texture and microstructure with varied applied pulse duration: for short pulse durations a lamellar microstructure with a {000ℓ} texture forms, whereas for longer pulse durations a more equiaxed and randomly oriented microstructure forms. The thermal conductivities of the pulsed electrodeposited films are surprisingly low at less than 2 W/K·m and are found to systematically decrease with reduced pulse time. - Highlights: ► We investigate the growth, microstructure, and thermal conductivity of Sb2Te3 films. ► Pulsed electrodeposition is used to grow crystalline Sb2Te3 films. ► Film composition and microstructure depend on the growth conditions. ► Kinetics and thermodynamics are used to explain these observations. ► The low thermal conductivities observed are correlated to microstructure and texture.